Banca de QUALIFICAÇÃO: ARNOBIO SILVA DE SOUZA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : ARNOBIO SILVA DE SOUZA
DATA : 15/12/2016
HORA: 14:30
LOCAL: Auditório do CCET/UFRN
TÍTULO:

Stratigraphic control in the framework and diagenetic evolution of the Tombador Formation, Mesoproterozoic of Chapada Diamantina, Bahia

PALAVRAS-CHAVES:

The siliciclastic deposits of the Tombador Formation, basal unit of the Chapada Diamantina Group, of mesoproterozoic age, occur in a north-south range along the Serra do Sincorá, central portion of the São Francisco Craton (CSF), Northeast Brazil. These deposits are formed by a thick sequence of low-grade metamorphic siliciclastic rocks (meta-sandstones). A petrographic and petrological study of thin sections of surface rocks of Tombador formation was carried out, along with the aid of special techniques such as X-Ray Fluorescence (FRX), X-ray Diffraction (XRD), X-ray Spectroscopy by Energy Dispersion (EDS) and Scanning Electron Microscopy (SEM). Based on the analyzes, it was verified that these rocks consist predominantly of meta-sandstones, ranging from medium to thick, locally bimodal. The following diagenetic events were identified: mechanical infiltration of clays, mechanical compaction, chemical compaction, quartz and tourmaline overgrowth, iron oxide film, grain dissolution, reflecting the evolutionary stages of diagenesis and telodiagenesis. The following chemical elements in descending order, Si, Al, K, Fe, Mg, Ti, Zr, Sr and Y were identified by X-ray fluorescence in total sample. The element Silicon (Si), with values above 85 %, indicates the high mineralogical maturity of these rocks. Through the XRD technique, the following groups of clay minerals were identified: Ilita, Caulinite, Esmectite, Ilite/Caulinite and Ilite/Esmectite strata. It was verified by ilite crystallinity index or "Kubler index" obtained by the measurement of the width of the peak of 10 Å, (full width at half maximum - FWHM) that these rocks reached the zone of the anchemimorphism, reaching to reach the anchizona. The diagenetic events of mechanical compaction and cementation were equally important in reducing the primary porosity of these rocks. The occurrence of certain clay minerals is directly related to the depositional environment, showing that the stratigraphic control and the composition of the framework are directly responsible for the diagenetic evolution of these rocks.

PÁGINAS: 101
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

Diagenetic evolution, clay minerals, anhimetamorphism, ilite crystallinity index

MEMBROS DA BANCA:
Externo ao Programa - 1884342 - DEBORA DO CARMO SOUSA
Presidente - 277437 - MARCELA MARQUES VIEIRA
Externo ao Programa - 347536 - NARENDRA KUMAR SRIVASTAVA